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C Magnoni

Publications and source records attributed to C Magnoni.

14 recordsLinked to original sources
PubMed2002

Ultraviolet B radiation induces activation of neutral and acidic sphingomyelinases and ceramide generation in cultured normal human keratinocytes.

The sphingomyelin pathway is an ubiquitous, evolutionary conserved signaling system which transduces an extracellular signal into the cell. During the past few years increasing evidence has shown that the sphingolipid ceramide may play a role as a second messenger in intracellular signal transduction. The ceramide generation via sphingomyelinase (SMase) is followed by three major cellular responses: cell growth arrest, induction of cell differentiation and/or induction of programmed cell death or apoptosis. The aim of this study is to investigate whether activation of SMases and generation of ceramide can be induced by UVB radiation in normal human keratinocytes. The present data show that exposure to UVB radiation results in rapid generation of ceramide. The ceramide accumulation starts 15 min after UV exposure and progressively increases up to 24 h. In vitro measurement of SMase activity following exposure to UVB evidences an activation of both neutral and acidic SMases. Moreover, UVB induces apoptosis in normal human keratinocytes as shown by TUNEL technique and FACS analysis. These data indicate that UVB induced ceramide generation and activation of both neutral and acidic SMases, suggesting that sphingolipids metabolism may be involved in the UVB signaling pathway.

Apoptosis↗
PubMed2000

Ceramide 2 (N-acetyl sphingosine) is associated with reduction in Bcl-2 protein levels by Western blotting and with apoptosis in cultured human keratinocytes.

BACKGROUND: Ceramides produced by sphingomyelin hydrolysis activate a cycle that is followed by three different major cellular responses: downregulation of cell proliferation, induction of cell differentiation and apoptosis. In the skin, the generation of intracellular ceramide may also provide a link between an extracellular signal and the induction of the apoptosis programme for the elimination of damaged cells. OBJECTIVES: We investigated the effect of ceramides capable of entering cells on cultured keratinocytes. METHODS: Human keratinocytes from neonatal skin were cultured in serum-free medium with or without increasing concentrations of ceramide 2 (CER-2; N-acetyl sphingosine) (5, 10, 20 and 40 micromol L-1). Proliferative effects were studied either by cell counts or by 3H-thymidine incorporation and flow cytometric analysis. Apoptosis was studied by TUNEL staining and Western blot analysis of Bcl-2 protein. RESULTS: Cell counts and DNA synthesis were reduced in a dose-dependent manner following CER-2 treatment. TUNEL staining showed CER-2-induced apoptosis at 48, 72 and 96 h. Western blot analysis showed that CER-2 induces downregulation of Bcl-2 at 24-96 h. CONCLUSIONS: These results demonstrate that CER-2 inhibits cell proliferation and induces apoptosis, possibly via a Bcl-2-dependent mechanism.

Apoptosis↗
PubMed2000

Thickness and echogenicity of the skin in children as assessed by 20-MHz ultrasound.

BACKGROUND: Skin anatomy and physiology undergo modifications throughout the whole lifespan. In children the skin appears with structural characteristics, as evaluated by histology, which differ from those of adults, especially in the first years of life. OBJECTIVE: The aim of our study was to evaluate skin thickness and echogenicity at different sites in children by 20-MHz ultrasound. METHODS: Eight skin sites of 42 children and 30 young adults were studied with a 20-MHz B scanner. Skin thickness and mean echogenicity were evaluated. The echographic images were processed and segmented by a dedicated program: the 0-30 amplitude interval, which marks the hypoechogenic parts of the tissue, and the 201-255 range, highlighting the hyperreflecting areas, have been selected. RESULTS AND CONCLUSION: Whereas skin thickness shows a gradual increase from birth to adulthood, maturation of the skin leads to variations in the intensity of its echogenicity, depending on the different skin areas. Whereas on the face and the trunk it appears lower in adults with respect to children, a gradual increase can be observed on the limbs with growing age. The distribution of skin reflectivity also greatly varies in different phases of life.

Adolescent↗
PubMed1997

Enhancement of DNA repair in human skin cells by thymidine dinucleotides: evidence for a p53-mediated mammalian SOS response.

Thymidine dinucleotide (pTpT) stimulates melanogenesis in mammalian pigment cells and intact skin, mimicking the effects of UV irradiation and UV-mimetic DNA damage. Here it is shown that, in addition to tanning, pTpT induces a second photoprotective response, enhanced repair of UV-induced DNA damage. This enhanced repair results in a 2-fold increase in expression of a UV-damaged chloramphenicol acetyltransferase expression vector transfected into pTpT-treated skin fibroblasts and keratinocytes, compared with diluent-treated cells. Direct measurement of thymine dimers and (6-4) photoproducts by immunoassay demonstrates faster repair of both of these UV-induced photoproducts in pTpT-treated fibroblasts. This enhanced repair capacity also improves cell survival and colony-forming ability after irradiation. These effects of pTpT are accomplished, at least in part, by the up-regulation of a set of genes involved in DNA repair (ERCC3 and GADD45) and cell cycle inhibition (SDI1). At least two of these genes (GADD45 and SDI1) are known to be transcriptionally regulated by the p53 tumor suppressor protein. Here we show that pTpT activates p53, leading to nuclear accumulation of this protein, and also increases the specific binding of this transcription factor to its DNA consensus sequence.

Cells, Cultured↗
PubMed1997

Autocrine nerve growth factor protects human keratinocytes from apoptosis through its high affinity receptor (TRK): a role for BCL-2.

Normal human keratinocytes synthesize and release nerve growth factor (NGF) and express both the low- and the high-affinity NGF receptor. Because NGF has been shown to rescue certain cell types from programmed cell death, we investigated the role of endogenous NGF in preventing keratinocyte apoptosis. We report here that apoptosis is induced in normal human keratinocytes in culture by blocking endogenous NGF signaling with either anti-NGF neutralizing antibody or K252, a specific inhibitor of the tyrosine kinase high-affinity NGF receptor. Apoptosis was assessed by DNA laddering, electron microscopy, and in situ nick end labeling technique. In anti-NGF-treated keratinocytes, the apoptotic process starts at 96 h, and is maximal at 120 h. After K252 treatment, apoptosis starts at 48 h and peaks at 120 h. Because the product of the bcl-2 proto-oncogene protects many cell types from apoptosis, we measured the levels of this protein in apoptotic keratinocytes. We found that both K252 and anti-NGF antibody strikingly downregulate bcl-2 expression, starting at 72 h. Furthermore, HaCat keratinocytes stably transfected with a plasmid containing bcl-2 cDNA fail to undergo apoptosis when treated with K252. These findings show that autocrine NGF acts as a survival factor for human keratinocytes in vitro through its high-affinity NGF receptor, possibly by maintaining constant levels of Bcl-2.

Apoptosis↗
PubMed1995

Nerve growth factor receptor and neurochemical markers in human oral mucosa: an immunohistochemical study.

BACKGROUND: The innervation of the oral mucosa has so far been studied mainly by histochemical and ultrastructural techniques. Only few studies have investigated the presence of neural proteins and neurotransmitters in human gingival mucosa. OBJECTIVE: The purpose of the present study was to evaluate the presence and distribution of neural structural and transmitter proteins in different areas of normal human oral mucosa. METHOD: Indirect immunofluorescence was employed on specimens taken from different mucosal regions (gingiva, lips, gums, palate). Both structural (low-affinity nerve growth factor receptor, NGFr; protein gene product 9.5, PGP 9.5) and neuropeptide markers (substance P; calcitonin gene-related peptide; vasoactive intestinal peptide, neuropeptide Y) were used. RESULTS: NGFr and PGP 9.5 intensely labelled both nerve fibres and selected epithelial cells, while neuropeptide immunoreactivity was scarcely expressed and exclusively localized in nerve fibres. CONCLUSIONS: Similarly in the distribution pattern and neurochemistry between oral and cutaneous innervation is apparent. Expression of NGFr could be relevant to the trophism of both the oral innervation and epithelium.

Adolescent↗
PubMed1994

Psoriasis and the nervous system.

Both clinical and experimental evidence is accumulating on the role of the nervous system in the pathogenesis of psoriasis. Sporadic reports as well as extensive studies indicate that emotional stress can act as an exacerbating event in psoriasis. Moreover, that neurogenic mechanisms are operating in psoriasis is suggested by clinical, pharmacologic and experimental data. We have focused our investigations on the role of vasoactive intestinal peptide (VIP) and substance P (SP) in psoriatic lesions using a variety of experimental approaches: 1) receptor autoradiography; 2) immunohistochemistry; 3) radio-immunoassay; 4) human keratinocytes cultures. Our results indicate that an imbalance of VIP and SP exists in psoriatic lesions, and that these neuropeptides exert different and specific effects on human keratinocytes. At present, however, the finding of psoriasis being exacerbated by psychological factors cannot be satisfactorily explained merely by alterations of neuropeptides in the skin.

Humans↗
PubMed1981

Immunogenicity of A/USSR (H1N1) subunit vaccine in unprimed young adults.

A clinical and serological study was performed on 267 of 636 volunteers vaccinated against Argentine hemorrhagic fever with the XJCl3 attenuated strain of Junin virus seven to nine years earlier, in order to determine their long-term evolution. This study included a clinical examination, a chest roentgenogram, an electrocardiogram, and the following laboratory determinations: white and red cell count, number of platelets, hematocrit, hemoglobin, sedimentation rate (Katz index), urea, nitrogen, glucose concentration, cholesterol, GOT, GPT, gamma GT, alkaline phosphatase, cholinesterase, and total bilirubin. Neutralization reactions were performed to determine presistence of antibody levels. All clinical and laboratory findings were within normal limits, excluding a long-term pathology attributable to the virus. Of 165 tested sera, 153 (90.3%) had detectable levels of neutralizing antibodies, and the rest had no antibodies after this time. Although these people live in the endemic area, it is considered that only the 9% that had increased antibody levels had suffered a reinfection during the seven- to nine-year period, which acted as a booster. This figure aproximately coresponds to the subclinical infection value found in the region. In the rest, the persistence of antibodies is attributed to the immunization achieved with the vaccine employed.

Adult↗
PubMed1981

Argentine hemorrhagic fever: early diagnosis by immunofluorescence.

A procedure that allows to ascertain a diagnosis of Argentine Hemorrhagic Fever (AHF) as early as 24-48 hours after onset of symptoms is described. An immunofluorescent (IF) test on round cells of urinary sediment was employed. The procedure was assayed on 31 patients with febrile syndrome during epidemic peaks of 1975-1976. It was positive in 19 and negative in 12 cases. The 19 positive cases were confirmed AHF by clinical follow up and serology. From 12 negative cases, 8 belonged to other etiologies and 2 were confirmed AHF. The usefulness of the procedure for early diagnosis is emphasized.

Antigens, Viral↗
PubMedDate not supplied

Decrease in toxic potential of mixed tensides maintained below the critical micelle concentration: an in vitro study.

Sodium lauryl sulphate (SLS) is an anionic tenside widely utilized in commercial topical preparations that may cause skin irritation. It has been shown that the barrier damage caused by SLS in vivo is lower when SLS is used in combination with other tensides which are able to reduce the critical micelle concentration (CMC). The aim of our study was to evaluate if the cytotoxic effect of SLS is reduced by the association with different tensides also at concentrations well below the CMC. Normal human keratinocytes from plastic surgery were grown in serum-free medium. At subconfluency, the cells were treated with SLS at a dose of 0.0025% in combination with cocamidopropyl betaine, Tween 20 and Tween 80 at the minimum toxic dose. Following tenside treatment, the culture medium was changed, and after 24 h the cells were collected for (3)H-thymidine incorporation, the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay and neutral red (NR) uptake. The cytotoxic effect on normal human keratinocytes, as evaluated by (3)H-thymidine incorporation, MTT assay and NR uptake, was significantly decreased by the combination with all the tested tensides. The correlation between cytotoxicity and physical properties was also studied by a conductimetric assay to investigate the mechanism involved in this toxicity reduction.

Betaine↗